1. Field of the Invention
The invention relates to fitting a spline to a user-defined freehand curve.
2. Description of the Related Art
Many image-related applications allow a user to draw a freehand curve. For example, a curve may be drawn to enclose a garbage matte area, to define a portion of an image to be tracked or to define a motion path. Such a curve is composed of a plurality of digitized points and is expensive both in computation and storage to manipulate and test. Thus a spline is usually fitted to a freehand curve, such a spline being made up of a plurality of discrete curves, usually joined with some degree of continuity.
However, it is often the case that such curve-fitting processes result in control points that are difficult to manipulate. In particular, many curve-fitting algorithms result in splines that have tangent handles, the slope and length of which define the curve, but often the handles are unbalanced, with one being much shorter than the other. Such a fitted curve can be difficult for a user to manipulate.